In the prior art, press sections are provided with frame parts such that the press fabrics can be removed and replaced by a new press fabric or fabrics as a closed loop. The frame parts must also be constructed so that, when necessary, the press rolls can be replaced and the different devices and components can be serviced without unreasonable work or disassembly of the machine.
As known in the prior art, the vertical frame parts at the tending side of the machine are provided with openable intermediate pieces, through which opened gaps the new press fabrics can be passed into their place as a closed loop. When the side frames at the tending side are opened, the frame part must be supported by means of an overhang, i.e., cantilevered, which takes place by the intermediate of a projecting part of the cross-direction beams of the frame part, which projecting parts extend to the driving side of the machine. These projecting parts are typically supported by means of draw bars or equivalent on the wall or floor constructions of the paper machine hall or on the base constructions of the press section on the lower parts of another frame part. The cross-direction projecting parts must be constructed to be quite long, and therefore they occupy a considerable space at the driving side of the machine. This requirement of space is increased further in view of the fact that the projecting parts have to be positioned with a very dense spacing and as an extension of almost every cross-direction beam at the driving side of the machine. This space would be necessary for the drive gears of the rolls in the press section and for devices for conditioning of the different fabrics and for other, similar devices. As an example of the prior art described above, reference is made to U.S. Pat. No. 5,535,670 assigned as issuance to J. M. Voith GmbH.
The numerous prior art cantilever beams which extend to the tending side of the machine divide the space provided at the driving side alongside the machine into small compartments, in which it is difficult to place and to service the drive gears of the press section and other devices and systems that are otherwise particularly suitable for these spaces.
The replacement of press rolls usually takes place so that the press rolls are shifted by means of a crane in the axial direction to the tending side of the machine while supporting the press rolls from their axle journals and possibly from between the axle journals by means of an overhead crane mounted on the ceiling. The current assignee has also constructed press sections in which free spaces can be opened above the press rolls by pivoting or otherwise shifting the frame parts, and through this space, it is possible to replace a press roll or rolls by lifting the same straight or substantially straight upwards and by introducing the new roll by means of the same procedure and along the same route into the place of the removed roll(s). With respect to the last-mentioned arrangements for replacement of press rolls and fabrics, reference is made to the current assignee's U.S. Pat. Nos. 4,452,668 and 4,608,125, incorporated by reference herein.
The cantilever arrangement described above results in considerable drawbacks, which are emphasized further in press sections in which separate nips or groups of nips are employed. These drawbacks are manifested with particular emphasis in press sections that comprise two separate extended nips, which press section is marketed by the current assignee under the trade mark SymBeltPress II.TM.. As known in the prior art, the frame system of this press section comprises two frame parts of substantially equal shape, which frame parts are interconnected from above by means of machine-direction upper beams in order to increase the rigidity of the frame.